Class: Nokogiri::XML::Reader

Inherits:
Object
  • Object
show all
Includes:
Enumerable
Defined in:
lib/nokogiri/xml/reader.rb,
lib/nokogiri/ffi/xml/reader.rb,
ext/nokogiri/xml_reader.c

Overview

Nokogiri::XML::Reader parses an XML document similar to the way a cursor would move. The Reader is given an XML document, and yields nodes to an each block.

Here is an example of usage:

reader = Nokogiri::XML::Reader(<<-eoxml)
  <x xmlns:tenderlove='http://tenderlovemaking.com/'>
    <tenderlove:foo awesome='true'>snuggles!</tenderlove:foo>
  </x>
eoxml

reader.each do |node|

  # node is an instance of Nokogiri::XML::Reader
  puts node.name

end

Note that Nokogiri::XML::Reader#each can only be called once!! Once the cursor moves through the entire document, you must parse the document again. So make sure that you capture any information you need during the first iteration.

The Reader parser is good for when you need the speed of a SAX parser, but do not want to write a Document handler.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#cstruct ⇒ Object

Returns the value of attribute cstruct.



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# File 'lib/nokogiri/ffi/xml/reader.rb', line 6

def cstruct
  @cstruct
end

#encoding ⇒ Object (readonly)

The encoding for the document



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# File 'lib/nokogiri/xml/reader.rb', line 37

def encoding
  @encoding
end

#errors ⇒ Object

A list of errors encountered while parsing



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# File 'lib/nokogiri/xml/reader.rb', line 34

def errors
  @errors
end

#reader_callback ⇒ Object

Returns the value of attribute reader_callback.



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# File 'lib/nokogiri/ffi/xml/reader.rb', line 7

def reader_callback
  @reader_callback
end

#source ⇒ Object (readonly)

The XML source



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# File 'lib/nokogiri/xml/reader.rb', line 40

def source
  @source
end

Class Method Details

.from_io(io, url = nil, encoding = nil, options = 0) ⇒ Object

Create a new reader that parses io



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# File 'ext/nokogiri/xml_reader.c', line 516

def self.from_io(io, url=nil, encoding=nil, options=0)
  raise(ArgumentError, "io cannot be nil") if io.nil?

  cb = IoCallbacks.reader(io) # we will keep a reference to prevent it from being GC'd
  reader_ptr = LibXML.xmlReaderForIO(cb, nil, nil, url, encoding, options)
  raise "couldn't create a parser" if reader_ptr.null?

  reader = allocate
  reader.cstruct = LibXML::XmlTextReader.new(reader_ptr)
  reader.send(:initialize, io, url, encoding)
  reader.reader_callback = cb
  reader
end

.from_memory(string, url = nil, encoding = nil, options = 0) ⇒ Object

Create a new reader that parses string



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# File 'ext/nokogiri/xml_reader.c', line 475

def self.from_memory(buffer, url=nil, encoding=nil, options=0)
  raise(ArgumentError, "string cannot be nil") if buffer.nil?

  memory = FFI::MemoryPointer.new(buffer.length) # we need to manage native memory lifecycle
  memory.put_bytes(0, buffer)
  reader_ptr = LibXML.xmlReaderForMemory(memory, memory.total, url, encoding, options)
  raise(RuntimeError, "couldn't create a reader") if reader_ptr.null?

  reader = allocate
  reader.cstruct = LibXML::XmlTextReader.new(reader_ptr)
  reader.send(:initialize, memory, url, encoding)
  reader
end

.node_namespaces(ptr) ⇒ Object 



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# File 'lib/nokogiri/ffi/xml/reader.rb', line 205

def node_namespaces(ptr)
  cstruct = LibXML::XmlNode.new(ptr)
  ahash = {}
  return ahash unless cstruct[:type] == Node::ELEMENT_NODE
  ns = cstruct[:nsDef]
  while ! ns.null?
    ns_cstruct = LibXML::XmlNs.new(ns)
    prefix = ns_cstruct[:prefix]
    key = if prefix.nil? || prefix.empty?
            "xmlns"
          else
            "xmlns:#{prefix}"
          end
    ahash[key] = ns_cstruct[:href] # TODO: encoding?
    ns = ns_cstruct[:next] # TODO: encoding?
  end
  ahash
end

Instance Method Details

#attribute(name) ⇒ Object

Get the value of attribute named name



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# File 'ext/nokogiri/xml_reader.c', line 202

def attribute(name)
  return nil if name.nil?
  attr_ptr = LibXML.xmlTextReaderGetAttribute(cstruct, name.to_s)
  if attr_ptr.null?
    # this section is an attempt to workaround older versions of libxml that
    # don't handle namespaces properly in all attribute-and-friends functions
    prefix_ptr = FFI::Buffer.new :pointer
    localname = LibXML.xmlSplitQName2(name, prefix_ptr)
    prefix = prefix_ptr.get_pointer(0)
    if ! localname.null?
      attr_ptr = LibXML.xmlTextReaderLookupNamespace(cstruct, localname.read_string)
      LibXML.xmlFree(localname)
    else
      if prefix.null? || prefix.read_string.length == 0
        attr_ptr = LibXML.xmlTextReaderLookupNamespace(cstruct, nil)
      else
        attr_ptr = LibXML.xmlTextReaderLookupNamespace(cstruct, prefix.read_string)
      end
    end
    LibXML.xmlFree(prefix)
  end
  return nil if attr_ptr.null?

  attr = attr_ptr.read_string
  LibXML.xmlFree(attr_ptr)
  attr
end

#attribute_at(index) ⇒ Object

Get the value of attribute at index



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# File 'ext/nokogiri/xml_reader.c', line 177

def attribute_at(index)
  return nil if index.nil?
  index = index.to_i
  attr_ptr = LibXML.xmlTextReaderGetAttributeNo(cstruct, index)
  return nil if attr_ptr.null?

  attr = attr_ptr.read_string
  LibXML.xmlFree attr_ptr
  attr
end

#attribute_count ⇒ Object

Get the number of attributes for the current node



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# File 'ext/nokogiri/xml_reader.c', line 238

def attribute_count
  count = LibXML.xmlTextReaderAttributeCount(cstruct)
  count == -1 ? nil : count
end

#attribute_nodes ⇒ Object

Get a list of attributes for the current node



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# File 'lib/nokogiri/xml/reader.rb', line 59

def attribute_nodes
  nodes = attr_nodes
  nodes.each { |v| v.instance_variable_set(:@_r, self) }
  nodes
end

#attributes ⇒ Object

Get a list of attributes for the current node.



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# File 'lib/nokogiri/xml/reader.rb', line 51

def attributes
  Hash[*(attribute_nodes.map { |node|
    [node.name, node.to_s]
  }.flatten)].merge(namespaces || {})
end

#attributes? ⇒ Boolean

Does this node have attributes?

Returns:

  • (Boolean) 


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# File 'ext/nokogiri/xml_reader.c', line 108

def attributes?
  #  this implementation of xmlTextReaderHasAttributes explicitly includes
  #  namespaces and properties, because some earlier versions ignore
  #  namespaces.
  node_ptr = LibXML.xmlTextReaderCurrentNode(cstruct)
  return false if node_ptr.null?
  node = LibXML::XmlNode.new node_ptr
  node[:type] == Node::ELEMENT_NODE && (!node[:properties].null? || !node[:nsDef].null?)
end

#default? ⇒ Boolean

Was an attribute generated from the default value in the DTD or schema?

Returns:

  • (Boolean) 


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# File 'ext/nokogiri/xml_reader.c', line 74

def default?
  LibXML.xmlTextReaderIsDefault(cstruct) == 1
end

#depth ⇒ Object

Get the depth of the node



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# File 'ext/nokogiri/xml_reader.c', line 254

def depth
  val = LibXML.xmlTextReaderDepth(cstruct)
  val == -1 ? nil : val
end

#each(&block) ⇒ Object

Move the cursor through the document yielding each node to the block



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# File 'lib/nokogiri/xml/reader.rb', line 67

def each(&block)
  while node = self.read
    block.call(node)
  end
end

#inner_xml ⇒ Object

Read the contents of the current node, including child nodes and markup.



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# File 'ext/nokogiri/xml_reader.c', line 437

def inner_xml
  string_ptr = LibXML.xmlTextReaderReadInnerXml(cstruct)
  return nil if string_ptr.null?
  string = string_ptr.read_string
  LibXML.xmlFree(string_ptr)
  string
end

#lang ⇒ Object

Get the xml:lang scope within which the node resides.



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# File 'ext/nokogiri/xml_reader.c', line 286

def lang
  val = LibXML.xmlTextReaderConstXmlLang(cstruct)
  val.null? ? nil : val.read_string
end

#local_name ⇒ Object

Get the local name of the node



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# File 'ext/nokogiri/xml_reader.c', line 350

def local_name
  val = LibXML.xmlTextReaderConstLocalName(cstruct)
  val.null? ? nil : val.read_string
end

#name ⇒ Object

Get the name of the node



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# File 'ext/nokogiri/xml_reader.c', line 366

def name
  val = LibXML.xmlTextReaderConstName(cstruct)
  val.null? ? nil : val.read_string
end

#namespace_uri ⇒ Object

Get the URI defining the namespace associated with the node



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# File 'ext/nokogiri/xml_reader.c', line 334

def namespace_uri
  val = LibXML.xmlTextReaderConstNamespaceUri(cstruct)
  val.null? ? nil : val.read_string
end

#namespaces ⇒ Object

Get a hash of namespaces for this Node



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# File 'ext/nokogiri/xml_reader.c', line 125

def namespaces
  return {} unless attributes?

  ptr = LibXML.xmlTextReaderExpand(cstruct)
  return nil if ptr.null?

  Reader.node_namespaces(ptr)
end

#node_type ⇒ Object

Get the type of readers current node



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# File 'ext/nokogiri/xml_reader.c', line 395

def node_type
  LibXML.xmlTextReaderNodeType(cstruct)
end

#outer_xml ⇒ Object

Read the current node and its contents, including child nodes and markup.



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# File 'ext/nokogiri/xml_reader.c', line 456

def outer_xml
  string_ptr = LibXML.xmlTextReaderReadOuterXml(cstruct)
  return nil if string_ptr.null?
  string = string_ptr.read_string
  LibXML.xmlFree(string_ptr)
  string
end

#prefix ⇒ Object

Get the shorthand reference to the namespace associated with the node.



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# File 'ext/nokogiri/xml_reader.c', line 318

def prefix
  val = LibXML.xmlTextReaderConstPrefix(cstruct)
  val.null? ? nil : val.read_string
end

#read ⇒ Object

Move the Reader forward through the XML document.



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# File 'ext/nokogiri/xml_reader.c', line 408

def read
  error_list = self.errors

  LibXML.xmlSetStructuredErrorFunc(nil, SyntaxError.error_array_pusher(error_list))
  ret = LibXML.xmlTextReaderRead(cstruct)
  LibXML.xmlSetStructuredErrorFunc(nil, nil)

  return self if ret == 1
  return nil if ret == 0

  error = LibXML.xmlGetLastError()
  if error
    raise SyntaxError.wrap(error)
  else
    raise RuntimeError, "Error pulling: #{ret}"
  end

  nil
end

#state ⇒ Object

Get the state of the reader



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# File 'ext/nokogiri/xml_reader.c', line 382

def state
  LibXML.xmlTextReaderReadState(cstruct)
end

#value ⇒ Object

Get the text value of the node if present



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# File 'ext/nokogiri/xml_reader.c', line 302

def value
  val = LibXML.xmlTextReaderConstValue(cstruct)
  val.null? ? nil : val.read_string
end

#value? ⇒ Boolean

Does this node have a text value?

Returns:

  • (Boolean) 


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# File 'ext/nokogiri/xml_reader.c', line 91

def value?
  LibXML.xmlTextReaderHasValue(cstruct) == 1
end

#xml_version ⇒ Object

Get the XML version of the document being read



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# File 'ext/nokogiri/xml_reader.c', line 270

def xml_version
  val = LibXML.xmlTextReaderConstXmlVersion(cstruct)
  val.null? ? nil : val.read_string
end